Of Choices, Failures and Asynchrony: The Many Faces of Set Agreement

Abstract. Set agreement is a fundamental problem in distributed computing in which processes collectively choose a small subset of values from a larger set of proposals. The impossibility of fault-tolerant set agreement in asynchronous networks is one of the seminal results in distributed computing. The complexity of set agreement in synchronous networks has also been a significant research challenge. Real systems, however, are neither purely synchronous nor purely asynchronous. Rather, they tend to alternate between periods of synchrony and periods of asynchrony. In this paper, we analyze the complexity of set agreement in a such a “partially synchronous” setting, presenting the first (asymptotically) tight bound on the complexity of set agreement in such systems. We introduce a novel technique for simulating, in fault-prone asynchronous shared memory, executions of an asynchronous and failure-prone messagepassing system in which some fragments appear synchronous to some process...

• Type: Conference
• Year: 2009
• Where: ISAAC
• Authors: Dan Alistarh, Seth Gilbert, Rachid Guerraoui, Corentin Travers
• Keywords: Algorithms, Fault-tolerant Set Agreement, ISAAC 2009, Lower Bound, Set Agreement